How to add NETWORK SERVICE to Users permission group?

I'm adapting an application from a different server, their installation guide tells me to

Add Server Name\Network Service identity to Users permission group.

So how can I?

I've tried:

• Via Computer Management, Groups, Users and adding it there, but it wasn't found (neither netname\NETWORK SERVICE nor BY AUTHORITY\NETWORK SERVICE).

What am I missing here? Thanks in advance.

1. From Administrative Tools > Computer Management, expand System Tools > Local Users and Groups > Groups.

2. Double-click the Users group and click Add. Click Locations and select your computer node.

3. Now:

   1. Type Network Service into the 'Enter the object names' OR

   2. Click Advanced, then Find Now and select it from the Search Results.